The invention relates to a coating machine with several process chambers that are located on arcs of a circle around a common center line which are each connected with a vacuum line and a gas line. The coating machine has a carousel with substrate location seats located coaxially to the center line. The purpose of this carousel is the transport of substrates that are to be coated in the process chambers.
Coating machines of the afore-mentioned type are sold by the Leybold company under the name "Circulus" for example for the purpose of coating optic data carriers by means of cathode sputtering and are therefore known. This known coating machine has a carousel that is designed like a star-shaped transfer arm, which moves the substrates that are to be coated from process chamber to process chamber in a clocked turning motion so that the substrates can undergo different treatment processes in the various process chambers. The evacuation and gas supply for each process chamber is independent from all the other process chambers so that monitoring features are provided for each process chamber in order to control the existing process conditions. With coating machines it is often desirable to operate several process chambers in parallel formation, in order to achieve high level of productivity. This is the case when hollow parts or similar objects are to be coated since with parts of this type the entire coating system can be applied in a single process chamber. If several process chambers are operated in parallel formation, one has to ensure that absolutely identical conditions exist in all process chambers. As a result of different decreases in the flow rate, evacuation pipes or gas supply lines of varying lengths lead for instance to varying pressures in the process chambers. It follows that it must be possible to control all process chambers individually and that they must be equipped with the necessary controlling and measuring equipment in order to create identical process conditions.